Re: [pve-devel] [PATCH qemu-server 1/1] fix 1734: clone VM: if deactivation fails demote error to warning

[Friedrich Weber <f.weber@proxmox.com>]

Thanks for tackling this! Can confirm this patch demotes the error to a
warning and lets the qmclone task succeed (with a warning). GUI shows
"Warnings: 1" and task log contains:

can't deactivate LV '/dev/foobar/vm-100-disk-0':   Logical volume
foobar/vm-100-disk-0 in use.
WARN: volume deactivation failed: foobar:vm-100-disk-0 at
/usr/share/perl5/PVE/Storage.pm line 1246.

Small nits in-line:

On 06/03/2024 11:47, Hannes Duerr wrote:
> When a template with disks on LVM is cloned to another node, the storage
> is first activated, then cloned and deactivated again after cloning.

s/storage is/volumes are/g

> 
> However, if clones of this template are now created in parellel to other

typo: parallel

> nodes, it can happen that one of the tasks can no longer deactivate the
> logical volume because it is still in use.  The reason for this is that
> we use a shared lock.
> Since the failed deactivation does not necessarily have consequences, we
> downgrade the error to a warning, which means that the clone tasks will
> continue to be completed successfully.
> 
> Signed-off-by: Hannes Duerr <h.duerr@proxmox.com>
> ---
>  PVE/API2/Qemu.pm | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
> index 69c5896..f1e88b8 100644
> --- a/PVE/API2/Qemu.pm
> +++ b/PVE/API2/Qemu.pm
> @@ -48,6 +48,7 @@ use PVE::DataCenterConfig;
>  use PVE::SSHInfo;
>  use PVE::Replication;
>  use PVE::StorageTunnel;
> +use PVE::RESTEnvironment qw(log_warn);
>  
>  BEGIN {
>      if (!$ENV{PVE_GENERATING_DOCS}) {
> @@ -3820,7 +3821,13 @@ __PACKAGE__->register_method({
>  
>  		if ($target) {
>  		    # always deactivate volumes - avoid lvm LVs to be active on several nodes
> -		    PVE::Storage::deactivate_volumes($storecfg, $vollist, $snapname) if !$running;
> +		    eval {
> +			PVE::Storage::deactivate_volumes($storecfg, $vollist, $snapname) if !$running;
> +		    };
> +		    my $err = $@;
> +		    if ($err) {
> +			log_warn("$err\n");
> +		    }

I think the extra \n adds an unnecessary newline here, which looks a bit
weird in the task log (though I'm not sure why the `chomp` in `log_warn`
doesn't remove the newline).

While at it, I think the four lines can be shortened to

> log_warn($@) if $@;

Though that might be too terse -- someone with more Perl experience than
me should judge that :)

>  		    PVE::Storage::deactivate_volumes($storecfg, $newvollist);
>  
>  		    my $newconffile = PVE::QemuConfig->config_file($newid, $target);